$(document).ready(function(){
	
	//jq判断输入是否为空
  $("#username").blur(function(){
	  var username = $("#username").val();
	  if(username==""){
		$("#img1").attr('src',"images/f.png");		  
	  }else{
		$("#img1").attr('src',"images/t.png");  
	  }
  });
  $("#password").blur(function(){
  	  var pwd = $("#password").val();
  	  if(pwd==""){
  		$("#img2").attr('src',"images/f.png");		  
  	  }else{
  		$("#img2").attr('src',"images/t.png");  
  	  }
  });
});